The present invention relates to hermetic terminal assembly construction and more particularly to a terminal pin insulating arrangement for a hermetic terminal structure adapted to be sealed along the periphery of an aperture in a chamber defining housing wall.
It is known in the art of hermetic terminal assemblies to employ a current carrying electrically connected and conductive terminal pin which is surrounded by an insulating sleeve member located on the inner portion of the pin on the inner apertured dish side face of the bottom wall of a cup-shaped body of the terminal pin. The outer peripheral rim of the cup-shaped body is sealed along the periphery of an aperture in a chamber defining wall and the terminal pin, including inner and outer pin portions, is sealed intermediate such pin portions in the apertured bottom wall of the cup shaped body along with the end of the insulating sleeve member surrounding the inner pin portion. Such a structural arrangement can be seen in U.S. Pat. No. 4,584,433, issued to Benjamin Bowsky et al on Apr. 22, 1986 and in U.S. Pat. No. 5,017,740, issued to Glenn A. Honkomp et al on May 21, 1991, these two patents further disclosing a well recess in the pin surrounding sleeve member to provide an extended oversurface or tortuous path between the surrounded inner terminal pin portion and the cup shaped body. Fuse-like areas are also disclosed in each of these two patents with U.S. Pat. No. 4,584,433 showing such fuse-like area within the well recess of the surrounding sleeve member on the inner face of the cup-shaped body and U.S. Pat. No. 5,017,740 showing such fuse-like area embedded in a polymeric rubber silicone coating on the outer face of the cup shaped body. In this regard, insulative coatings on the outer face of terminal cup bodies have been generally well and long known in the art, attention being directed to U.S. Pat. No. 3,160,460, issued to A. Wyzenbeck on Dec. 8, 1964; U.S. Pat. No. 3,988,053, issued to John A. Dodenhoff on Oct. 26, 1976; U.S. Pat. No. 4,252,394, issued to Austin S. Miller on Feb. 24, 1981; U.S. Pat. No. 4,296,275, issued to Benjamin Bowsky on Oct. 20, 1981; and U.S. Pat. No. 4,609,774, issued to David M. LeMieux et al on Sep. 2, 1986.
The present invention recognizes that such outside insulative coatings as used in the prior art have been comparatively expensive and complex in materials, manufacture, application, durability and maintenance, necessarily requiring a uniformly even body surface for application and having limitations in bonding ability and resistance to degradation with temperature variations accompanied by occasional "doming" of the body surface during high pressure operations. The present invention recognizing these deficiencies in the prior art outside insulative coating practices provides for an economic and straightforward insulating structure which accommodates for high temperature variations and which allows for indentations of the cup shaped body member, resisting possible "doming" as a consequence of high pressures in the hermetically sealed housing chamber. In addition, the present invention provides for the economical, low cost use of existing materials, allowing for ready manufacture and assembly with minimal maintenance and, at the same time, insuring extended oversurfaces to reduce the possibilities of undesirable arcing. Further, the present invention allows for unitary manufacture of substantially identical mirror-image sleeve pairs when so desired, thus reducing the costs and number of process operations and, at the same time, providing terminal pin shielding.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.